1. Field of the Invention
The present invention relates to a gear unit comprising a shaft, a gear, and a stopper.
2. Description of the Related Art
An image forming device, for example, has a gear unit for driving various rollers. Japanese Patent Application Publication No. 2000-321836, for example, teaches an image forming device comprising a gear unit. As shown in FIG. 1 of that document, the gear unit comprises a base member, a shaft extending from the base member, and a gear that rotates with the shaft as its axis. The gear is capable of moving along the shaft. The stopper is fixed to the base member. The majority of the stopper is disposed outwards, with respect to the gear, in the radial direction of the gear. A part of the stopper is disposed in a position that interferes with the gear, when the gear moves along the shaft (upward in FIG. 1 of the document). As a result, in the case where the gear is moved along the shaft when the gear unit is to be attached to a main body of the image forming device, the gear makes contact with the stopper and consequently the gear does not drop off from the shaft.